An experimental drug with Durham roots is pushing Gilead shares to new heights.

Shares of Gilead Sciences Inc. (Nasdaq: GILD), the California-based company that closed on its purchase of drug developer Pharmasset Inc. in January, were at a record high Monday following favorable mid-stage clinical data for an experimental hepatitis C treatment. Pharmasset, which was based in New Jersey, developed the candidate, sofosbuvir, in part with research from scientists at Duke University.